PRODUCTS, ADVENTITIOUS. 



viscid, and free from solid particles of any 

 kind. And the evolution of all kinds of blas- 

 tema proceeds in the same manner, as far as 

 hitherto ascertained, until the formation of 

 cells is effected. The successive steps may 

 in general terms be stated to be increase of 

 viscidity, formation of granules, of nuclei, and 

 of cells.* And these various steps cannot be 

 accomplished except in blastema in contact 

 with living animal structure, a blastema 

 loses its potentiality either by the death of 

 the textures amid which it is evolved, or by 

 its removal from among them. We place no 

 confidence in the experiments upon which a 

 statement of certain exceptions to this law 

 has been founded, f 



No matter what be the ultimate destiny of 

 the blastema, the process of its evolution is 

 conducted, then, on the same principle ; but 

 the development of cells sets a limit to this 

 identity of process. The vital qualities of the 

 cells differ, and affect the function and end of 

 these, in three principal modes ; and, accord- 

 ing as each of these prevails in any given 

 blastema, will the product generated (solid or 

 semi-solid) present peculiar characters. These 

 three modes of cell may be described as fol- 

 lows. 



First, the cells once developed may be alto- 

 gether inapt for life, incapable either of under- 

 going such changes in physical, chemical, and 

 vital constitution as shall qualify them for sus- 

 taining a permanent existence, or of generating 

 the elements of new cells previous to their own 

 destruction. They are consequently acted 

 upon physically and chemically by the sur- 

 rounding materials : they are either dissolved 

 by the fluid with which they are associated ; 

 or, disintegrated and broken down into non- 

 productive granular matter, they lose all trace 

 of the attributes of organization. Cells of this 

 kind may be termed evanescent and retro- 

 grading. 



Secondly, the cells may be deficient in the 

 faculty of permanency requisite for the forma- 

 tion of tissue ; while, on the other hand, they 

 possess the power of generating the elements 

 of new cells (or of causing indirectly the 

 generation of those elements) previously to 

 their own disappearance, cells endowed in 

 turn with a similar generative force. These 

 cells consequently present the characters of 

 the formative stages of evolution, never those 

 of perfectly evolved structure. To this kind 

 of cells the title non-permanent and vegetative 

 may be applied. 



Thirdly, the cells may possess an inherent 

 force, qualifying them to pass through the 

 necessary steps towards the formation of 

 structure more or less closely resembling the 

 natural tissues, and in this evolved condition 

 they are destined permanently to remain. 

 These cells appear likewise to be destitute of 



* The production of fibres without the interven- 

 tion of a cell-stage (an exceptional phenomenon, if 

 the entire system be taken in view) will find its place 

 elsewhere. 



t Helbert, de exanthematibus arte factis. Gott. 

 1844. 



103 



the power either of generating or of indirectly 

 causing the generation of the elements of new 

 cells similar to themselves ; they may there- 

 fore be termed permanent and non-vegetative 

 cells. 



From cells of one or other of these three 

 kinds all blastemal formations are produced. 

 Formations produced from the evanescent cell 

 are non-stromal, and may be termed deposits ; 

 those from the vegetative cell are stromal, and 

 may be termed groivths ; those from the 

 permanent cell are stromal, and may be termed 

 pseudo-tissues, 



ORDER I. DEPOSITS. 



Deposits are deficient in the characters of 

 texture ; they possess neither permanent fibre, 

 nor definite arrangement of parts, septa, nor 

 loculi ; and are insusceptible of vascularization. 

 They tend to produce eliminatory action and 

 ulceration in the seats they occupy ; and are 

 prone to appear, mainly through the influence 

 of so-called " diathesis," in several parts of the 

 frame simultaneously or consecutively. The 

 substance of all deposits is per sc non-inocu- 

 lable ; we say all, because, though the point 

 has not been, to our knowledge, experimentally 

 tested in regard of the typhous and diphtheritic 

 species, there can be little doubt that the 

 proposition applies to them as to the others. 

 But certain varieties of one genus of deposit 

 (pus) are, on the contrary, readily inoculable 

 through the agency of certain associated 

 principles called viruses (see Pus). In such 

 coses, be it observed, the propagation of the 

 disease in no wise depends on the cell of the 

 fluid. 



In the order Deposits (constituting transi- 

 tion products from the non-plastic protein- 

 precipitates to formations of higher attributes) 

 we place the following genera : typhous, tuber- 

 culous, purulent, melanic, and diphtheritic pro- 

 ducts. 



1. TYPHOUS DEPOSIT. 



In the form of continued fever anatomically 

 characterized by alteration of structure in the 

 glandular textures of the small intestine, a 

 peculiar substance of new formation (as first 

 accurately described by M. Louis*) is dis- 

 covered in the cellular membrane between 

 the mucous and muscular coats of the patches 

 of agminated glands of Peyer. The propor- 

 tion of cases of continued fever of intestinal 

 type in which this deposit occurs, has been 

 differently estimated from less than one third 

 of the cases to nearly the entire number. We 

 have found this matter homogeneous in aspect, 

 of pinkish or yellowish hue (the former acci- 

 dental), and from a sixth to a quarter of an 

 inch thick ; we have always seen it more or 

 less firm and tenacious, and never succeeded 

 in catching it in its earlier stage of fluid 

 blastema. Examined under the microscope 

 by Bohmf it appeared utterly destitute of 



* Roedercr and "Wagler (De morbo mucoso, p. 

 332.) first noticed this siibstance thus : " ne semel 

 tamen elevatos [folliculos coagmentatos] et materia 

 mucosa obscure cinerea rcpertos vidimus." 



f Brit, and For. Med. Rev. vol. i. p. >- 1. 



H 4- 



